Hi Les, Perhaps I did not express my point clearly. My intention was not to say that implementors *only* look at IANA codepoints. I said often not always :) They sure look at RFCs too.
My point was that if I need to decode something - IANA gives me sort of decode cheatsheet and reference to RFC. It's type of dictionary in networking. We do not have alternative I am afraid and having protocols be defined in bunch of RFCs and sometimes still in drafts makes it a bit of a challenge to find the right one. Even flags in a number of cases are added in subsequent documents so even if you know to look at base spec then you need to follow "Updated by XYZ ..." and dig via a lot of text to find an answer instead of just a simple one page table lookup. Many thx, R. On Wed, Mar 17, 2021 at 4:31 AM Les Ginsberg (ginsberg) <ginsb...@cisco.com> wrote: > Robert – > > > > My experience with Wireshark does not match yours. > > > > In my experience, packet decoders aren’t always up on the latest spec > revisions – it is always a catchup game – but it isn’t true that only > values from an IANA registry are displayed. > > And from an implementation standpoint, the engineer writing the decoder > always has to look at the draft/RFC. An IANA Registry does not provide the > format of the fixed fields (e.g., prefix, metric) – so I have a hard time > agreeing with your perception that implementors only look at IANA > registries. > > I actually think it is the other way round – they look at drafts/RFCs and > only look at registries when the document points to them. 😊 > > > > Les > > > > > > *From:* Robert Raszuk <rob...@raszuk.net> > *Sent:* Tuesday, March 16, 2021 4:46 PM > *To:* Les Ginsberg (ginsberg) <ginsb...@cisco.com> > *Cc:* Alvaro Retana <aretana.i...@gmail.com>; lsr@ietf.org; Christian > Hopps <cho...@chopps.org> > *Subject:* Re: [Lsr] When is an IANA Registry Required > > > > Hi Les, > > > > I would like to share my personal experience that when debugging network > issues say using wireshark or tcpdump often dissectors only decode what is > in IANA registry. Anything beyond they print as hex. > > > > Sure if someone needs to decode it he or she will find an RFC where all > fields are described. But this usually requires manual labor we as lazy > humans are not always best at. > > > > So just from pure convenience (while I do understand heavy labor to move > all flags to IANA) there is some operational value I could see doing it. > > > > Best, > > Robert. > > > > > > On Tue, Mar 16, 2021 at 11:24 PM Les Ginsberg (ginsberg) <ginsberg= > 40cisco....@dmarc.ietf.org> wrote: > > Alvaro - > > > > Thanx - as always - for the thoughtful response. > > > > I would like to state up front that I would never consider you to be a > "casual reader". 😊 > > > > I am also glad you are opening this topic up to comments from others - > that was my intent as well. > > > > But one thing I find missing in your response is some info on what problem > YOU think needs to be addressed? > > Do you think there have already been cases where assignment of the bits in > the flags field associated w a prefix or a neighbor or other object > comparable to the new TLVs defined in draft-ietf-lsr-isis-srv6-extensions > (e.g., Locator) has become confusing due to the lack of a registry? > > I'd like to think you are motivated by more than a theoretical concern but > have at least one example based on your many years of experience working on > protocols. > > Such an example would help me understand your motivation better and might > even convince me that this is a good idea. > > > > Thanx. > > > > Les > > > > > > > > > -----Original Message----- > > > From: Alvaro Retana <aretana.i...@gmail.com> > > > Sent: Tuesday, March 16, 2021 12:39 PM > > > To: Les Ginsberg (ginsberg) <ginsb...@cisco.com>; > draft-ietf-lsr-isis-srv6- > > > extensi...@ietf.org > > > Cc: John Scudder <j...@juniper.net>; lsr-cha...@ietf.org; lsr@ietf.org; > > > Christian Hopps <cho...@chopps.org> > > > Subject: Re: When is an IANA Registry Required > > > > > > On February 27, 2021 at 12:57:12 PM, Les Ginsberg wrote: > > > > > > > > > Les: > > > > > > Hi! > > > > > > Sorry for the delay... > > > > > > §4/rfc8126 presents some general arguments for creating registries. > > > But let's talk about this specific case. > > > > > > > > > I'm taking the liberty of summarizing your message this way: > > > > > > > Historically, we have created IANA registries for identifiers which are > > > > likely to be needed by a variety of unrelated features supported by the > > > > protocol. The expectation in these cases is that multiple documents - > > > > largely unrelated to each other - might need to allocate an ID from the > > > same > > > > space. > > > ... > > > > What we have NOT done, historically, is create a registry for a flags > field > > > > which is not provided as a general purpose mechanism, but is > specifically > > > > scoped for use only within the context of the feature which defined the > > > > TLV/sub-TLV. (There are many examples.) > > > > > > > > It is expected in these cases that if an additional flag is required, > that > > > > it will be defined in a document directly related to the original > feature – > > > > either a bis version of the original document or a new document which > is > > > > marked specifically as an update to the original document. > > > > > > > > > In general, the expectations about the future use of a specific field > > > (as you describe them) are not always obvious to the casual reader[*]. > > > If the intent was clear, and the expectation ("bis...an update") is > > > spelled out in the document then I would not ask about the management > > > of the bits. And even better, future specifications (when maybe none > > > of us are around anymore) would have clear guidance. > > > > > > Having said that, and knowing that I am not the responsible AD for lsr > > > anymore, I would be very happy if the WG decided on requiring future > > > documents to be clear about the intended use and any requirements for > > > the allocation of flags or other unassigned bits. > > > > > > > > > Thanks for starting this discussion! I hope to see other opinions. > > > > > > Alvaro. > > > > > > [*] Anyone else besides maybe the authors themselves, including me. > > > > > > > > > > > > > Alvaro - > > > > > > > > In your review of draft-ietf-lsr-isis-srv6-extensions you requested the > > > > authors to > > > > > > > > "Please ask IANA to set up a registry for the Flags." > > > > > > > > in multiple cases e.g., the flags field defined in the new SRv6 > Capabilities > > > > sub-TLV. > > > > > > > > This isn't the first time you have made such a request (I believe I > argued > > > > against this in the past and you relented – but only temporarily it > seems. > > > 😊 > > > > ). > > > > > > > > As it is a deviation from historical practice, I think it would be > better if > > > > the WG discussed whether there is a good reason to change our practices > > > > rather than have this request be made based on the personal preference > > > of the > > > > current AD. > > > > > > > > Historically, we have created IANA registries for identifiers which are > > > > likely to be needed by a variety of unrelated features supported by the > > > > protocol. The expectation in these cases is that multiple documents - > > > largely > > > > unrelated to each other - might need to allocate an ID from the same > > > space. > > > > > > > > Obvious examples are TLV/sub-TLV code points. > > > > > > > > In the case of flags, there are currently only two such registries: > > > > > > > > link-attribute bit values for sub-TLV 19 of TLV 22 > > > > (https://www.iana.org/assignments/isis-tlv-codepoints/isis-tlv- > <https://www.iana.org/assignments/isis-tlv-codepoints/isis-tlv-codepoints.xhtml#isis-tlv-codepoints-19of22> > > > codepoints.xhtml#isis-tlv-codepoints-19of22 > <https://www.iana.org/assignments/isis-tlv-codepoints/isis-tlv-codepoints.xhtml#isis-tlv-codepoints-19of22> > ) > > > > > > > > Bit Values for Prefix Attribute Flags Sub-TLV > > > > (https://www.iana.org/assignments/isis-tlv-codepoints/isis-tlv- > <https://www.iana.org/assignments/isis-tlv-codepoints/isis-tlv-codepoints.xhtml#prefix-attribute-flags> > > > codepoints.xhtml#prefix-attribute-flags > <https://www.iana.org/assignments/isis-tlv-codepoints/isis-tlv-codepoints.xhtml#prefix-attribute-flags> > ) > > > > > > > > In both of these cases the sub-TLVs were defining a general purpose bit > > > > field. It was expected (and it has happened) that unrelated documents > had > > > a > > > > need to allocate a bit in these fields. > > > > > > > > What we have NOT done, historically, is create a registry for a flags > field > > > > which is not provided as a general purpose mechanism, but is > specifically > > > > scoped for use only within the context of the feature which defined the > > > > TLV/sub-TLV. (There are many examples.) > > > > > > > > It is expected in these cases that if an additional flag is required, > that it > > > > will be defined in a document directly related to the original feature > – > > > > either a bis version of the original document or a new document which > is > > > > marked specifically as an update to the original document. > > > > > > > > Management of the flag space in such cases has never required the > > > overhead of > > > > a registry. > > > > > > > > You seem to want to change that and I would like to know why? > > > > > > > > What problem exists that you are trying to solve? > > > > > > > > IMO, such a policy is not needed, does not add value, but does add > > > additional > > > > overhead to what is already a considerable set of hoops which drafts > must > > > > navigate on their way to becoming an RFC. > > > > > > > > The number of existing TLV/sub-TLVs which have flags fields is > significant – > > > > and the lack of a registry for these fields has not yet caused any > problem. > > > > > > > > Appreciate if we could have open discussion on this. > > > > > > > > Les > > _______________________________________________ > Lsr mailing list > Lsr@ietf.org > https://www.ietf.org/mailman/listinfo/lsr > >
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